It's correct to have punctiation at the end of a sentence. It does look awkward having a bracket followed by a full stop, but then, if you want to apply an exclamation to the remark in parenthesis, you'll have to write it that way.

I was reading the translation of Wim Wenders' The Act of Seeing and there the translator had a footnote that ended thus: ...(Trans.).I guess that publishers use different system of punctuation. The above-mentioned book is Faber&Faber's and their stuff is very different that, say, Routledge.However the same subject's been also discussed at:http://www.painintheenglish.com/post.asp?id=180

If you don't use the period, you should put the exclamation outside the parentheses. The phrase inside the parentheses is not a sentence (It is a continuation of the sentence.), and does not need its own period or exclamation.

Have fun in your meeting (or don't have fun at all)!orHave fun in your meeting. (Maybe you won't have fun at all!)